This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A351893 #11 Feb 26 2022 10:11:14 %S A351893 0,4,12,16,48,52,60,64,96,100,108,112,240,244,252,256,288,292,300,304, %T A351893 336,340,348,352,480,484,492,496,528,532,540,544,576,580,588,592,1440, %U A351893 1444,1452,1456,1488,1492,1500,1504,1536,1540,1548,1552,1680,1684,1692,1696 %N A351893 Numbers that contain only even digits in their factorial-base representation. %C A351893 All the terms are multiples of 4 (A008586). %H A351893 Amiram Eldar, <a href="/A351893/b351893.txt">Table of n, a(n) for n = 1..14400</a> (terms below 10!) %H A351893 Wikipedia, <a href="https://en.wikipedia.org/wiki/Factorial_number_system">Factorial number system</a>. %H A351893 <a href="/index/Fa#facbase">Index entries for sequences related to factorial base representation</a>. %e A351893 4 is a term since its factorial-base presentation, 20, has only even digits. %e A351893 16 is a term since its factorial-base presentation, 220, has only even digits. %t A351893 max = 7; fctBaseDigits[n_] := IntegerDigits[n, MixedRadix[Range[max, 2, -1]]]; Select[Range[0, max!, 2], AllTrue[fctBaseDigits[#], EvenQ] &] %Y A351893 Cf. A007623, A008586, A351894. %Y A351893 Subsequence: A052849 \ {2}. %Y A351893 Similar sequences: A005823 (ternary), A014263 (decimal), A062880 (quaternary). %K A351893 nonn,base %O A351893 1,2 %A A351893 _Amiram Eldar_, Feb 24 2022